Fibrous structures, even textured and/or embossed fibrous structures, comprising a plurality of filaments and solid additives, for example fibers, are known in the art. However, such known fibrous structures contain two regions, not three or more regions, that exhibit different values for a common micro-CT intensive property as measured according to the Micro-CT Test Method. Nor do such known fibrous structures contain two regions that exhibit different values for a micro-CT basis weight as measured according to the Micro-CT Test Method and exhibit different values for light transmission as measured according to the Light Transmission Test Method.
Prior Art FIG. 1 shows an example of a known method 100 for making a known fibrous structure 10 comprising a plurality of filaments and solid additives, wherein the fibrous structure is imparted texture by an embossing operation. This known method 100 fails to create a fibrous structure 10 comprising three or more regions that exhibit different values for a common micro-CT intensive property as measured according to the Micro-CT Test Method. Further, such method 100 fails to produce a fibrous structure 10 that contains two regions that exhibit different values for a micro-CT basis weight as measured according to the Micro-CT Test Method and exhibit different values for light transmission as measured according to the Light Transmission Test Method. As shown in Prior Art FIG. 1, the method 100 comprises the step of mixing a plurality of filaments 12 with a plurality of solid additives 14. In one example, the solid additives 14 are wood pulp fibers, such as SSK fibers and/or Eucalyptus fibers, and the filaments 12 are polypropylene filaments. The solid additives 14 may be combined with the filaments 12, such as by being delivered to a stream of filaments 12 from a hammermill 66 via a solid additive spreader 67 to form a mixture of filaments 12 and solid additives 14. The filaments 12 may be created by meltblowing from a meltblow die 68. The mixture of solid additives 14 and filaments 12 are collected on a collection device, such as a belt 70 to form a fibrous structure 10. A forming vacuum 17 aids in the collection of the solid additives 14 and filaments 12 onto the collection device, by pulling air through the collection device. The resulting fibrous structure 10 is passed through an embossing roll nip 69 to yield a finished, textured fibrous structure 10.
Fibrous structures made by a method as described in Prior Art FIG. 1 have uniform basis weight distribution of a plurality of filaments and solid additives which therefore renders the fibrous structure restricted to deliver an overall performance level characteristic of the fibrous structure possessing such uniform, overall basis weight and composition of the plurality of filaments and solid additives. In other words, a fibrous structure exhibiting an uniform basis weight of a plurality of filaments and solid additives, results in the fibrous structure exhibiting the same performance and properties across the entire fibrous structure.
The performance of a fibrous structure as measured by its strength, burst, flexibility, absorbency, and/or visual aesthetics properties which may be a function of its microstructure as measured by intensive properties such as basis weight, thickness, density, bonding, composition, etc. The overall performance of a fibrous structure may be increased by creating regions within the structure where intensive properties including basis weight, thickness, density, bonding, composition, and combinations thereof, are transformed or made to be different so as to have a region delivering high levels of one performance attribute in one region and then high levels of another performance attribute in others. Having different regions with differing high levels of performance in one fibrous structure yields overall performance levels superior to a uniform fibrous structure. For example, the overall performance of the fibrous structure may be maximized by having regions within the fibrous structure which are responsible for delivering one performance requirement such as strength, while a separate region delivers a separate performance requirement such as absorbency or visual aesthetics, and yet another region delivers a performance requirement such as flexibility.
The delivery of overall fibrous structure performance within a region is directly related to the intensive properties imparted to the regions. The ability to spread the intensive property property features or values across three or more regions may provide overall higher fiber structure performance while minimizing negatives such as wetted fibrous structure transparency. For example, if basis weight within a region is reduced excessively, then this region in a wetted fibrous structure or wet wipe configuration, may be viewed as see though or too transparent by consumers. Such a negative may be minimized through a fibrous structure comprising three or more regions.
Therefore, a problem that has not been addressed by known fibrous structures comprising a plurality of filaments and a plurality of solid additives, such as fibers, is the creation of fibrous structures that comprise three or more regions that exhibit at least one common micro-CT intensive property that differs in value, and separately, fibrous structures comprising two regions that exhibit different values for a micro-CT basis weight as measured according to the Micro-CT Test Method and exhibit different values for light transmission as measured according to the Light Transmission Test Method and methods for making same.
In light of the foregoing, there is a need for a fibrous structure that comprises three or more regions that exhibit at least one common micro-CT intensive property that differs in value, and separately, fibrous structures comprising two regions that exhibit different values for a micro-CT basis weight as measured according to the Micro-CT Test Method and exhibit different values for light transmission as measured according to the Light Transmission Test Method that overcome the negatives of the known fibrous structures without such regions and methods for making such fibrous structures.